"""
Berechnung von Zete(3)
(c) Jürgen Meier
www.3d-meier.de
21.06.2024
"""



p = 0
k = 100
for n in range(0, k + 1):
    p = p + (1.0/((5*n+1)**3) -1.0/((5*n+2)**3)+ 1.0/((5*n+3)**3)- 1.0/((5*n+4)**3)+ 1.0/((5*n+5)**3))*((-1.0)**n)
print(4*p/3)